1. Field of the Invention
This invention relates to emulsion copolymers useful as thickening or gelling agents for water-miscible organic liquids, and, more particularly, to a thicknening compositions comprising an emulsion copolymer of vinylacetate and a monoester of an unsaturated dicarboxylic acid and a water-miscible organic liquid.
2. Description of the Prior Art
The preparation of gels by the addition of natural or synthetic compounds to water or organic liquids is well known in the art. For example, U.S. Pat. No. 2,773,811 describes the preparation of aqueous gels by the use of natural and synthetic gums. U.S. Pat. No. 3,101,300 teaches the formation of an oil-water gel by the addition of acid-alkanolamide and an aliphatic polyglycolether phosphate. In Brit. Pat. No. 961,478, a non-thixotropic fuel gel is prepared by using the combination of an acid-functional polyelectrolyte and polyallylsucrose. Several other patents describe similar gelled systems using various gelling agents. However, the formation of these gels necessitates polymers with crosslinked structures which prevent the movement of the liquid. The gelation in the prior art is brought about by the swelling of the polymer as a consequence of the penetration of the liquid through the polymeric network, and therefore, the nature of the gel depends upon the affinity between the polymer and the liquid, wherein it can be either hydrophilic or hydrophobic.